Photographic developer



Patented Got. 12, 1937 f TA PHOTOGRAPHEC DEVELOPER Harold ll). Russell, Rochester, N. Y., assignor, by

mesne assignments, to EastmanKodak Company, Jersey City, N.

Jersey 3., a corporation of New No Drawing. Application May 6, 1936,

Serial No. 78,171

8 Claims.

This invention relates to photographic developers and particularly to alkalies for use in a photographic developer in the dry form.

In my prior Patent No. 1,976,299 I have described a photographic developer which may be compounded in the dry form, using sodium metaborate as the alkaline constituent. The sodium metaborate described in this patent may contain various amounts of water of crystallization. I have described in my prior patent sodium metaborate containing either four or eight molecules of water of crystallization. The alkalinity of a photographic developer prepared with one of these compounds as the alkaline constituent is limited by the solubility of borax, since a portion of the metaborate is converted into borax, in some developer solutions, by the acid constituents of the developer. The concentration of the metaborate must therefore be adjusted so that insufiicient borax is formed in solution to precipitate from the developer solution. A further diiiiculty is that certain alkalies, such as caustic soda, when mixed in dry form with the sodium metaborate, having eight molecules of water of crystallization, absorb water from the metaborate which causes the mixture to become moist. For this reason a combination of this particular metaborate and the caustic alkali cannot be used satisfactorily in packaged developers prepared in the dry form.

It is, therefore, an object of the present invention to provide a photographic developer in dry form more alkaline than sodium metaborate. A further object is to provide a developer in dry form which does not become moist or cake when packed in a reasonably tight container.

These objects are accomplished by the present invention by mixing the sodium metaborate containing four or less molecules of water of crystallization with a more alkaline material to increase the alkalinity of the developer without increasing the tendency of the mixture to become moist or cake when packed in the dry form. I have found that while the sodium metaborate containing eight molecules of Water of crystallization when mixed with powdered caustic soda will become moist, the modification containing four molecules of water of crystallization may be mixed with caustic soda or other alkali in varying amounts and will retain its dry form when packed in a reasonably tight container.

The Na2B2O4-4HZO used in the developer according to my invention may be prepared by mixing an alkali metal hydroxide and an alkali metal salt of tetraboric acid as described in my prior Compound Ka Amino acetic acid l 1. 8xl0- 1. 3xl0- Triethanolamine lxl0- Phosphoric acid (3rd H+) 3. 61110- Carbonic acid (2nd 11+). 6xl0- Meta silicic acid 1x10- Caustic alkalies which may be used include sodium and potassium hydroxides. These compounds are water-soluble whereas the alkaline earth metal hydroxides are for the most part insoluble in water.

The proportion of alkaline compounds to metaborate which may be used according to my invention may vary over wide ranges. In general, the caustic alkalies will be used in proportions of about one-half of the amount of the sodium metaborate and may vary from this proportion down to a very small amount of caustic alkali with a major amount of sodium metaborate. The other alkaline compounds mentioned above may be used in amounts greater or less than the amount of the sodium metaborate.

The alkaline materials used with the sodium metaborate in addition to having preferably nondeliquescent properties should also be readily soluble in the developer solution and at least as strong an alkali as the sodium metaborate, and soluble in the fixing bath or stop bath which is used in the photographic processes. It is, of course, possible to use an alkaline material which is less alkaline than the metaborate. However; this will usually be undesirable, since the activity of the developer depends on its alkalinity and a more alkaline material will usually be desired.

As examples of developers which may be compounded according to my invention I will cite the following, which are stated'by Way of example only. The following developer mixtures are made up to be used with one liter of water to make a developer solution. The developing agents are usually separated from the other ingredients in the package.

Example 1 7 Grams Monomethylparaniinophenol Sulfate 6 Hydroquinone r. 3 Sodium sulfite 30 Potassium bromide -r 1 Sodium metaborateAI-IZO Sodium hydroxide 10 Example 2 Grams Monomethylparaminophenol sulfate l. Hydroquinone 4 Sodium sulfite 30 Potassium bromide 0.5 Sodium metaborateAI-EO 20 Trisodium phosphate r. 20

Example 3 Grams Monomethylparaminophenol sulfate 2.5 Hydroquinone 2.5 Sodium sulfite a- 30 Potassium bromide w 0.5 Sodium metaborateAI-IzO 10 Sodium metasilicate 10 Developers of the above type'are usuallypacked in a two compartment container.- The developing agents are packed in one compartment and the akali, sulfite, bromide, etc., packed in the other compartment. t

In describing my invention I have placed special emphasis on the use of sodium metaborate containing four molecules of water of crystallization. This modification may be used in preparing developers in dry form when mixed with caustic soda or other alkali. Obviously, sodium metaborate with less than four molecules of water of crystallization could likewise be used and would not cake when mixed with more deli v quescent alkaline compounds. Other metaborates which can be used are the anhydrous modification and the one containing only one molecule of-water of crystallization. However, the

manufacture of sodium metaborate with less than four molecules of water of crystallization is difficult and expensive, and for this reason I prefer to use the modification containing four molecules of water of crystallization.

What I claim is:

1. A" dry, non-caking alkaline material for use in photographic developers comprising essential- 13! sodium metaborateAHzO and a compound selected from the group consisting of water-soluble caustic alkalies and water-soluble alkaline saltsv of acid compounds having a dissociation constantof less than 1x 10- 2. A dry non-caking alkaline material for use in photographic developers comprising essentially sodium metaborate.4I-Iz0 and a water-soluble alkaline salt of an acid compound having a dissociation constant of less than 1 x 10- 3. A dry, non-caking alkaline material for use in photographic developers comprising essentially sodium metaborate/lHzO and a water-soluble caustic alkali.

4. A dry, non-caking alkaline material for use in photographic developers comprising essentially sodium metaborate.4I-lz0 and a water-soluble caustic alkali, the sodium metaborate and the caustic alkali being present in approximately equal proportions.

5. A dry, non-caking alkaline material for use in photographic developers comprising essentiallysodium metaborate.4I-Iz0 and sodium hydroxide.

6. A dry, non-caking alkaline material for use in photographic developers comprising essentially sodium metaborateHzO and sodium hydroxide, the sodium metaborate and the sodium hydroxide being present in approximately equal proportions. v

7. A dry, non-caking alkaline material for use in photographic developers comprising essentially sodium metaborateAHzO and trlsodium phosphate.

8. A dry, non-caking alkaline material for use in photographic developers comprising essentially sodium metaborateAI-IzO and sodium metasilicate.

HAROLD D. RUSSELL. 

